Gene-diet interactions in gastric cancer risk: A systematic review

AIM:To conduct a systematic review of the published epidemiological studies investigating the association of the interactions between gene variants and dietary intake with gastric cancer risk.METHODS:A literature search was conducted in PubMed,EMBASE,and MEDLINE for articles published between January 2000 and July 2013,and 38 studies were identified.Previous studies included various dietary factors(e.g.,fruits and vegetables,soybean products,salt,meat,and alcohol)and genetic variants that are involved in various metabolic pathways.RESULTS:Studies suggest that individuals who carry high-risk genetic variants and demonstrate particular dietary habits may have an increased risk of gastric cancer compared with those who do not carry high-risk genetic variants.Distinctive dietary patterns and variations in the frequency of genetic variants may explain the higher incidence of gastric cancer in a particular region.However,most previous studies have limitations,such as a small sample size and a retrospective casecontrol design.In addition,past studies have been unable to elucidate the specific mechanism in gene-diet interaction associated with gastric carcinogenesis.CONCLUSION:Additional large prospective epidemiological and experimental studies are required to identify the gene-diet metabolic pathways related to gastric cancer susceptibility.

Effect of dietary vitamin C on gastric cancer risk in the Korean population

AIM: To investigate the effects of dietary vitamin C and foods containing vitamin C on gastric cancer risk.METHODS: Our study included 830 control subjects and 415 patients. Data regarding demographics, medical history, and lifestyle, including dietary and nutrient intake, were collected using reliable selfadministered questionnaires. Dietary intake information was collected from the participants using a food frequency questionnaire that has been previously reported as reliable and valid. A rapid urease test and a histological evaluation were used to determine the presence of Helicobacter pylori(H. pylori) infection. Twenty-three vitamin C-contributing foods were selected, representing over 80% of the cumulative vitamin C contribution. RESULTS: In analyses adjusted for first-degree family history of gastric cancer, education level, job, household income, smoking status, and regular exercise, an inverseassociation between vitamin C intake and gastric cancer risk was observed for the highest(≥ 120.67 mg/d) vs the lowest(< 80.14 mg/d) intake category [OR(95%CI): 0.64(0.46-0.88)], with a significant trend across the three intake categories(P = 0.007). No protective effect of vitamin C was detected after stratification by gender. No effect of vitamin C intake on the gastric cancer incidence was found in either men or women infected with H. pylori. Vitamin C-contributing foods, including cabbage [0.45(0.32-0.63), 0.50(0.34-0.75), 0.45(0.25-0.81)], strawberries [0.56(0.40-0.78), 0.49(0.32-0.74), 0.52(0.29-0.93)], and bananas [0.40(0.29-0.57), 0.41(0.27-0.62), 0.34(0.19-0.63)], were protective factors against the risk of gastric cancer based on the results of the overall adjusted analyses and the results for men and women, respectively.CONCLUSION: A protective effect of vitamin C and vitamin C-contributing foods against gastric cancer was observed. Further studies using larger sample sizes are required to replicate our results.

Colorectal cancer mortality in Hong Kong of China,Japan,South Korea,and Singapore

To clarify the trend in colorectal cancer mortality in Asian countries.We analyzed the colorectal cancer mortality in four Asian countries using the World Health Organization mortality database and the Korea National Statistics Office database.The annual age-standardized rates and truncated rated for the three age groups(30-49,50-69 and ≥ 70 years) for Hong Kong of China(1969-2009),Japan(1955-2009),South Korea(1985-2006),and Singapore(1966-2009) were estimated.A joinpoint regression model was used to detect significant trends in mortality rates.Colorectal cancer mortality in men started to decrease in 1992 in Japan followed by Singapore and Hong Kong of China in 1995.The mortality rates in women stared to decrease in 1980 in Singapore,followed by Hong Kong of China and Japan in 1996.In all countries and both genders,except for women in Singapore,the decrease in mortality began in the younger age groups.The colorectal cancer mortality in the four studied Asian countries has started to decrease,and the decrease occurred first in the younger age groups.

Dietary flavonoid intake and risk of stomach and colorectal cancer

Stomach and colorectal cancers are common cancers and leading causes of cancer deaths.Because the alimentary tract can interact directly with dietary components,stomach and colorectal cancer may be closely related to dietary intake.We systematically searched published literature written in English via PubMed by searching for terms related to stomach and colorectal cancer risk and dietary flavonoids up to June 30,2012.Twenty-three studies out of 209 identified articles were finally selected for the analysis.Log point effect estimates and the corresponding standard errors were calculated using covariate-adjusted point effect estimates and 95%CIs from the selected studies.Total dietary flavonoid intake was not associated with a reduced risk of colorectal or stomach cancer [odds ratio(OR)(95%CI) = 1.00(0.90-1.11) and 1.07(0.70-1.61),respectively].Among flavonoid subclasses,the intake of flavonols,flavan-3-ols,anthocyanidins,and proanthocyanidins showed a significant inverse association with colorectal cancer risk [OR(95%CI) = 0.71(0.63-0.81),0.88(0.79-0.97),0.68(0.56-0.82),and 0.72(0.61-0.85),respectively].A significant association was found only between flavonols and stomach cancer risk based on a limited number of selected studies [OR(95%CI) = 0.68(0.46-0.99)].In the summary estimates from casecontrol studies,all flavonoid subclasses except flavones and flavanones were inversely associated with colorectal cancer risk,whereas neither total flavonoids nor any subclasses of flavonoids were associated with colorectal cancer risk in the summary estimates based on the cohort studies.The significant association between flavonoid subclasses and cancer risk might be closely related to bias derived from the case-control design.There was no clear evidence that dietary flavonoids are associated with reduced risk of stomach and colorectal cancer.

Colors of vegetables and fruits and the risks of colorectal cancer

AIM To investigate the relationship between the colors of vegetables and fruits and the risk of colorectal cancer in Korea.METHODS A case-control study was conducted with 923 colorectal cancer patients and 1846 controls recruited from the National Cancer Center in Korea. We classified vegetables and fruits into four groups according to the color of their edible parts(e.g., green, orange/yellow, red/purple and white). Vegetable and fruit intake level was classified by sex-specific tertile of the control group. Logistic regression models were used for estimating the odds ratios(OR) and their 95% confidence intervals(CI).RESULTS High total intake of vegetables and fruits was strongly associated with a reduced risk of colorectal cancer in women(OR = 0.32, 95%CI: 0.21-0.48 for highest vs lowest tertile) and a similar inverse association was observed for men(OR = 0.60, 95%CI: 0.45-0.79). In the analysis of color groups, adjusted ORs(95%CI) comparing the highest to the lowest of the vegetables and fruits intake were 0.49(0.36-0.65) for green, and 0.47(0.35-0.63) for white vegetables and fruits in men. An inverse association was also found in women for green, red/purple and white vegetables and fruits. However, in men, orange/yellow vegetables and fruits(citrus fruits, carrot, pumpkin, peach, persimmon, ginger) intake was linked to an increased risk of colorectal cancer(OR = 1.61, 95%CI: 1.22-2.12).CONCLUSION Vegetables and fruits intake from various color groups may protect against colorectal cancer.